96 Chevy Caprice (LT1) cylinder 4 misfire
#1
96 Chevy Caprice (LT1) cylinder 4 misfire
I have a 96 Chevy Caprice (LT1), under a load I have a constant misfire on cylinder 4, I've swapped the injector from cylinder 2 to cylinder 4, yet the misfire remains on cylinder 4. I've changed the plug and wire on 4 (and all other cylinders a couple of months prior). And the distributor cap was also changed a few months prior to that. At a loss of what it could be, any help is much appreciated. Thank you.
#2
Does it set a code ?
How many miles ?
So , it has a distributor ? Not a coil pack or coil over plug ?
Are you getting fire to that plug .
Was both the distributor cap and rotor changed at the same time ?
If high mileage , do a compression test ?
God bless
Wyr
How many miles ?
So , it has a distributor ? Not a coil pack or coil over plug ?
Are you getting fire to that plug .
Was both the distributor cap and rotor changed at the same time ?
If high mileage , do a compression test ?
God bless
Wyr
#3
Sets P0304, GENISYS shows misfire on 4 only (but only under a load), otherwise no miss.
~277k miles, It has a distributor (Opti-Spark), plug is getting fire
Cap and rotor were changed at the same time.
Compression test was performed ~2 months ago (all was well).
~277k miles, It has a distributor (Opti-Spark), plug is getting fire
Cap and rotor were changed at the same time.
Compression test was performed ~2 months ago (all was well).
#4
Can you hear any spark jumping ( in places it should not ) at idle ?
Old school test , wait until night , good and dark . Raise the hood . Start the car . Look under hood for " fire jumping " .
Just for grins , swap # $ plug with another one .
God bless
Wyr
Old school test , wait until night , good and dark . Raise the hood . Start the car . Look under hood for " fire jumping " .
Just for grins , swap # $ plug with another one .
God bless
Wyr
#5
There aren't any signs of spark jumping, but there is no misfire at idle, only under a load (shortly after driving) it shows #4 misfiring repeatedly. Right before changing the wire (a couple of days ago) the plug on #4 was changed.
#6
I am running out of ideas / suggestions .
Anything metal closer to # 4 plug than it should be ?
Gap on # 4 plug verified ?
Visually inspect plug # 4 , especially the porcelain ?
Are any of the other plug wires close enough in length to # 4 wire , to swap ?
God bless
Wyr
Anything metal closer to # 4 plug than it should be ?
Gap on # 4 plug verified ?
Visually inspect plug # 4 , especially the porcelain ?
Are any of the other plug wires close enough in length to # 4 wire , to swap ?
God bless
Wyr
#7
#4 plug is clear of any metal, plug has been visually inspected (and changed recently), problem remains, gap has been verified. Yesterday evening I purchased a new set of plug wires and placed a new wire on #4 and the problem remains.
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#8
Stab in the dark . Check all the sensors . Check wiring & connectors . Check all vacuum devices & tubing . Look into the underside of the distributor cap for carbon tracking .
Swap plugs .
God bless
Wyr
Swap plugs .
God bless
Wyr
#10
You say it misfires under load ?
It is my impression that the greater the load , the greater the demand in the ignition system , to produce a good , effective , reliable spark .
I do not know if this means the resistance at the gap increases as load goes up ? Perhaps requiring higher voltage , to make the spark jump ?
If so , then perhaps the higher voltage gives those little electrons an opportunity to jump at locations they are not suppose to ?
Best of luck . :-)
God bless
Wyr
It is my impression that the greater the load , the greater the demand in the ignition system , to produce a good , effective , reliable spark .
I do not know if this means the resistance at the gap increases as load goes up ? Perhaps requiring higher voltage , to make the spark jump ?
If so , then perhaps the higher voltage gives those little electrons an opportunity to jump at locations they are not suppose to ?
Best of luck . :-)
God bless
Wyr
Last edited by WyrTwister; February 2nd, 2017 at 6:13 AM.